Process for washing containers



y 1950 H. n. LATHROP ETAL ,5 ,003

PROCESS FOR WASHING CONTAINERS Filed Jan. 8, 1942 the spraying operation automatically creating a foam in addition to washing the cans. The foam so formed is carried downwardly by the water stream and the water and foam returned in a stream or by any means to the main pool or reservoir of washing liquid.

Any suitable material for combining with milk fats and other milk ingredients and impurities or for enveloping the same to form a floating layer and for producing a foam body sufficient to support such materials upon the liquid may be employed. Since such materials are well known to those skilled in the art, it is believed unnecessary to describe them in detail. The ingredients may be alkali or acid, as desired.

A suitable acid-cleaning solution, which may be employed, comprises, in addition to the water employed, an enzyme, such as pepsin, gluconic acid, for imparting the definite acid reaction, lecithin as the emulsifier for fat substances, and a wetting agent which may have emulsifying and enveloping properties, such as sulphonated alcohol or sulphonated petroleum fractions. In such an aqueous washing solution, there may be one part lecithin, nine parts pepsin, about 2% of wetting agent, and a sufficient acid to carry the pH on the acid side, e. g., 6.4. In view of the fact that detergents are known which, in the washing of the cans, will give a foaming effect while emulsifying or combining with the fat, it is believed unnecessary to give examples or a detailed statement of proportions. Any suitable solution of this type which combines with or emulsifies fat and produces a foam body, maintaining the removed fat and impurities in a body upon the top of the wash liquid, may be employed. The foam-forming and treating ingredients are added to the reservoir in such proportion as to make all of the wash water therein foam-forming in character so that when such water is sprayed under pressure into the interior and onto the exterior of the cans for the cleansing operation, it automatically produces a foam body which carries the fat and other impurities as above described. In adding an increment of water and fresh ingredients for the purpose of producing an overflow and an elimination of the foam body and layer, it is important to add ingredients combined with the fresh water so as to maintain the foam-forming quality of the wash Water within the reservoir.

The fresh water used to replenish the wash water may be introduced from any source. It is often desirable to return a portion of the hot rinse water used in a succeeding operation or from a preceding operation. The ingredients may be added at any point in the treating process.

While the ingredients may be introduced as desired into the reservoir, we much prefer to introduce them into freshly emptied cans as a pretreating step and just prior to the main washing step in which wash Water is Withdrawn from the reservoir below the foam level thereof and introduced into the can. We find that the pretreating step just described, in which the fresh ingredients are given an opportunity to meet and combine with or envelop the fats and other impurities, is effective in preparing the can interior or exterior for the quick removal of such fats and impurities when it reaches the main washing step. Such pretreating provides a time interval in which the combination with, envelopment or emulsifying of the fats, milk solids, or impurities is carried through to the desired degree, enabling the resulting compounds to be readily removed upon being struck by the wash water. The ingredients employed in the pretreating step are carried to the reservoir tank and together with the make-up water result in an overflow of the top layer carried by the liquid level. The overflow may pass through a longitudinal slot adjacent the upper level of the liquid or it may overflow from any open edge provided by the tank. The foamy material thus withdrawn may, if desired, be used for washing the exteriors of the cans or for any purpose.

With the above-described process, it is found that the wash water need not be drawn off for replenishing as a whole, but may be constantly used with the effectiveness of fresh wash water while the undesirable ingredients which ordinarily contaminate wash water are automatically removed. The process is extremely simple, enabling washing to be carried on more quickly and effectively with the use of less ingredients and washing liquid. With the present process, it is possible to reuse in the washing tank substantially all of the hot rinse feed water, a considerable portion of which was formerly allowed to go to waste, thus resulting in a saving of heat. In the reuse of the Wash water, there is no tendency for a recontamination of surfaces by deposits of milk fats, milk stone, water stone, foreign matter, molds, yeasts, bacteria, etc., because these foreign materials have been removed by overflowing the foam layer at the top of the liquid and because the Wash water is withdrawn at a point well below such layer.

After the can leaves the washing station, it is carried to a rinse station, where hot rinse water is applied to the inside and outside of the can, the hot water being preferably returned as a whole to the wash water tank. In the rinsing step, the hot water is delivered under pressure and at a temperature above boiling at atmospheric pressure before releasing it into the can. Following this, the can is subjected to a clear feed water rinse at relatively high temperature, such as, for example, 200 B.

After the rinsing step, the surfaces of the can carry water in bead-like forms which are dimcult to dissipate. In order to readily remove these, we apply a very light spray of acid cleaner of the type heretofore described, which diminishes the surface tension and causes the water to flow from the can. By following this'operation, it

is possible to omit any steam application and still maintain higher temperatures. In the final step, the can is preferably dried with air.

Apparatus is shown in the accompanying drawing with which the new method may be carried out. Such apparatus is old for the most part and need not be described in detail. In the illustration given, l0 designates a frame providing a can track II and a can cover track l2. In the operation of such machines, the cans and covers are advanced step-by-step by pivotal pawls carried by reciprocating rails. I3 designates the top portion of pawls employed for advancing the cans, as shown more clearly in Fig. 2. The pawls advance the cans from one station to another and, at the various stations where the cans and covers pause, specific operations, such as draining, washing, rinsing, drying, etc., are carried on. For example, a number of such operating stations are indicated by the numerals l4, l5, l6, ll, l8, I9, 20, 2| and 22. Stations It and 15 are. usually employed for draining stations, the drained material from station 14 being caught by the drip saver pan 23. Station It is usually employed for a cold wash. Station I! is employed preferably for the application of the foamtormina in redients heron, es.- ioe examn m throu h nozzle 2 as shown more: clearly in Fi 2;. t tation. it is preferred to; direct the mam-formin in r di nts as a fresh core centrated solution directly into. the; can to; meet and combine with or envelop the: fats other impurities intherpretreating openatiomwhich has already; been described; the: resulgtmg; foam and. water pass directhyzinto tank 25. When. the cam reaches the station It, it; met; by? a washing? solutiom from the: reseisvoin tanle 252: just. be-- low, and thefoam-fonming'ingredients. within the can areagitated and: removed-5 its a foaming mass; dropping.- into. the reservoir 2:5: therebelew'; At station IS; the can; is preferably allowed to drain. The: rinsing operation with hot: water is next. carried on atstatlbia 2:0; and the filial application. of i a light spray oh the acid cleaner is made. at station 22; If desired; two rinsing stati'ons: may-be used. single ontwo-rinsihg stations and 2 l may-be usedz I-t will be understood that in the; foregoing canw-ashing station, suitable nozzles areemployed at the various statigns for introducing the washipgliquidganglirinsihg solutions, etc. In subsequent operations; at the following station 22 the can will. be. allowed; to, drain and then will be dried by application of hot air. In stepbyesteprelation, the can covers above-the cans Iii? are given exactly the same treatment at" each station. In; the final; welleknoy n; operation, the can is inverted and the cone;- is automatically placed. uponthe can, and each can withnts own e er ssmqye away by suitableme anism. In View of thewell-known construction of allot. the foregoing it is believed unnecessary tojsett, out a detailed, description of sugh oldelementst,

In Fig.2 a portion of. the. cas ing is; broken away to show the overflow tank and therlnozzle at,,stati,on, l'fi is removed} tQLShQWI the nozzle; at station.l"l.,.

Suitable structure herein, by, which the foam overflows from the pooh and is removedis; setout,in,the. t1lree figures of the-drawing. A foam tank 2s is' secured to the sida casing ES Ofgthe reservoir tank and communicatesewith theetank wh t nt alln eh ut s ength throughislot drawr pineshlt smevcsth oam at a later stagaand carries itpreferably to;.the,-:,rear end of the machine for use inwashing the can exteriors.

In -thesoperation of the/structure shown-inflic drawings, the caneat. station lill-ireceives the-concentrated application of acid cleaner in a pretreating operation in which the ingredients of the solution are permitted to work effectively upon the fats and impurities within the can. The can, upon arrival at station l8, meets a large volume of hot wash water, which produces a large volume of persistent foam which floats with the impurities and fats upon the surface of the liquid. The water below the surface is thus protected from contamination with the fats and other impurities by the foam and is repeatedly used in the washing operations at stations [8 and I9. The foam completely covers the wide surface of the tank and overflows along one side through the slots 38 into a settling tank 28 in which the foam tends to break and the liquid containing some foam is led away through pipe 3|.

The pump 32, as indicated in Fig. 1 of the drawing, serves to draw wash liquid from below the surface in tank and to discharge it upward-ly thmugha nozzle. thecan at tionliaz It he understood-that, whiiie the: has: beem. deseriheads herein isrcoimcdtiom with aacan, is; also used in; commotion. the of the can and withothear of containers. and maybe; also= used: with plastic; metal, and a. greatvariety ofi otherrsnrfiacesz While we have; the: intention in: comnection with certaim details. and specific.- steps,v it will be. understood thatthoseski llediin the may and will depart; fronr such. details, and specific steps; while. still: employing. our invention.

We claim:

1., In. a: process; for: washing; emptied; cans containing milk films on. the: surfaces; theneufil the; steps of maintaining; a; Pool: of? wash: containing: ingredients; in: proper propontimiwith the. liquid to form Withz solidssazfiaams agitated, spraying fresh; and: sneh foam:- forming; ingredients onto; can: surlfiaces: toe preetr-ea-tthe; same-,-. collecting; the: liquid andifiam carried thereby and directing the; same; torv saidi' pool, withdrawing; wash. liquid, from said: pool belo wlsaidfoamylayerandisprayixrgetheisamesontm surfaces of: said. pretreated cam, andz retuminm such usede wash liquidi and: the foam. la en? prosduced-xtherebyl to saidmeseevoir whereimsaidzfoanr layer is; caused to; overflow the; added: inure? mentof,- freslaliquid. and, foam-forming; ilzleredia ents;

2. In, aNprocess-lfor washing emptied mills canacontaining, milk. films; on the. surfaces theredtg,v the, steps. of. maintaining a. n ck of; wash.- liquid; containing ingredients, in, propen proportions-tot form with, milk. solids. a; foam! when agitated, sprayihgjfizesh. liquid-, containing. such; ingredients;- onto.v cansurfaces. ion pretreatment directinggtha liquid" and foamnthusproduced to. said noohwhera said foam body collects upon the top; of said; liquid, withdrawing. Wash'lliquifilfrombelbwv said top level' and introducing, thesame; under, pres,v sure onto surfaces. offsaid", can, ,r.eturnihg, suclil used'liquid and the foam producedutotsaidip'ooli andremoving the foam layer fromtliejop of the: liquidWithirr-said p001;

3' 111* a process forywashing; emptied" containing" milk. components. on. the surfaces thereof; thegsteps ofmaintaining;a.moolioffwasliiiv liquid containing; ingredients in: proper pronor t-ion; with the li'quid to formrwitllv milk,solitls a. foam when agitated, sprayihgg li'quidjcontainifig such-- foam--forn-ii'ngingredients onto can' sun faces to remove milk components and to form a foam with such ingredients, collecting the liquid and foam carried thereby and directing the same to said pool, withdrawing wash liquid from said pool below said foam layer and spraying the same onto surfaces of said prewashed can, and returning such used wash liquid and the foam layer produced thereby to said reservoir, wherein said foam layer is caused to overflow by the added ingredient of fresh liquid and foam-forming ingredients.

4. In a process for washing emptied milk cans containing milk components on the surfaces thereof, the steps of maintaining a pool of wash liquid containing ingredients in proper proportion to form with milk solids a foam when agitated, spraying liquid containing such ingredients onto can surfaces carrying milk components to form a foam holding said components, directing the liquid and foam, thus produced, to said pool where said foam body collects upon the top off-said liquid, withdrawing wash liquid from below said top level and introducing the same under pressure onto surfaces of said can, returning such used liquid and the foam produced to said pool, and removing the foam layer from the top of the liquid within said pool.

; In a process for washing emptied milk cans containing milk components on the surfaces thereof, the steps of maintaining a pool of wash liquid containing ingredients in proper proportion to form with milk solids a foam when agitated, spraying liquid containing such ingredients onto can surfaces containing such milk components to form a foam therewith, directing the liquid and foam, thus produced, to said pool where said foam body collects upon the top of said liquid, withdrawing wash liquid from below said top level and introducing the same under pressure onto surfaces of said can, returning such used liquid and the foam produced to said pool, rinsing the washed can with fresh liquid and returning rinsing liquid to said pool whereby said foam layer is caused to overflow by the added increment of said liquid. 6. In a process for washing emptied milk cans containing milk components on the surfaces thereof, the steps of maintaining a pool of wash liquid containing ingredients in proper proportion to form with milk solids a foam when agitated, spraying liquid containing such ingredients onto can surfaces carrying milk components, directing the resulting foam with the liquid to said pool where said foam body collects upon the top of said liquid, withdrawing wash liquid from below said top level and introducing the same under pressure onto surfaces of said can, returning such used liquid and the foam produced to said pool, rinsing the washed can with fresh hot water, and returning at least a portion of such hot water used in rinsing to said pool to cause said foam layer to overflow.

7. In a process for washing emptied milk cans containing milk components on the surfaces thereof, the steps of maintaining a pool of wash liquid containing ingredients in proper proportion to form with milk solids a foam when agitated, spraying liquid containing such ingredients on can surfaces containing milk components to form a foam, directing the liquid and foam, thus produced, to said pool where said foam body collectsupon the top of said liquid, withdrawing washliquid from below said top level and introducing the same under pressure onto surfaces of 8 said can, returning used liquid and the foam produced to said pool, rinsing the washed can with hot water in the neighborhood of a boiling temperature, and returning hot rinse water from said operation to said 'pool to cause said foam layer to overflow.

8. In a process for washing emptied milk cans containing milk components on the surfaces thereof, the steps of maintaining a pool of wash water containing ingredients in proper proportion to form with milk solids when agitated a floating body, spraying liquid containing such ingredients on can surfaces containing milk components to form such body, directing the liquid body thus produced into said pool where said body collects upon the top of said liquid, withdrawing wash liquid from below said top level and introducing the same under pressure onto surfaces of said can, returning used liquid and the floating body produced to said pool, rinsing the washed can with hot water in the neighborhood of 200 F., and returning said hot water from said rinsing operation to said pool to cause said floating body to overflow. V

HARRY D. LATHROP. VERGIL SCHWARZKOPF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,512,918 Forsgard Oct. 28, 1924 1,633,396 Clarin June 21, 1927 1,642,419 Loew Sept. 13, 1927 1,732,552 Chapman Oct. 22, 1929 1,854,235 Stoddard Apr. 19, 1932 1,932,070 Grant et a1 Oct. 24, 1933 1,950,630 Ries Mar. 13, 1934 2,006,085 Lehmkuhl June 25, 1935 2,057,286 Ash Oct. 13, 1936 2,070,487 Lutz Feb. 9, 1937 Re. 20,490 McLean et a1 Aug. 31, 1937 2,127,017 Walker Aug. 16, 1938 2,197,602 Wolcott Apr. 16, 1940 2,236,445 Pfeiffer Mar. 25, 19 11 2,262,955 Miller Nov. 18, 1941 2,291,085 Lehmkuhl et a1 Jul 28, 1942 2,338,689 Parker et a1. Jan. 4, 1944 FOREIGN PATENTS Number Country Date 729,214 France Apr. 25, 1932 

